Discrete circuits have been used in conventional laser-based measurement systems because the discrete circuit components are simple and inexpensive. However, the parasitic effects related to physical size, configuration, and interconnections of the components of the discrete circuits make it difficult to detect and process very small signals. To overcome these deficiencies, laser-based measurement systems have relied on increased laser power, increasingly larger arrays of photodiodes, and computing resource intensive signal processing methods.
Photodiodes have been used to convert optical signals (in the form of a photon flux) to an electrical signal in the form of a charge flux (current) in conventional laser-based measurement systems. These photodiode currents are often in the picoamp (pA) range, and signals of such low magnitude are difficult to detect and process with conventional discrete circuit techniques. Integrated circuit technologies allow for the use of component values that are smaller than discrete circuit values, and also allow the use of signal processing methods that are difficult or impossible to implement using discrete level components.
While there has been integrated circuit development work applied to increasingly larger arrays for imaging applications with some digital imaging products exceeding 40 million pixels per sensor, the design methods used for large imaging array integrated circuits introduce many of the same problems associated with discrete level implementations due to the required interconnection of parts.
Accordingly, there is a need for a laser-based measurement system with a unified network dedicated to the use of a single detector or small number of detectors.